Effect of steady magnetic field on microstructure and properties of laser cladding Ni-based alloy coating

Abstract

In this paper, Ni-based alloy coating was prepared on pure iron substrate by steady magnetic field assisted laser cladding technology. The influence mechanism of steady magnetic field on the Ni-based coating was investigated by analyzing the macro-morphology, phase composition, microstructure, element composition and properties of the coatings, respectively. The results reveal that external magnetic field can restrain the surface fluctuation of the coatings. It has no effect on the phase composition of the coatings. Compared with the coating prepared without magnetic field assistance, the grains of the coatings prepared under the magnetic induction intensities of 0.1 T, 0.15 T and 0.2 T are all refined. The solid solubility of the γ-Ni matrix is also increased. Hard phases CrB in the microstructures appear clustered aggregation and preferential orientation with the increase of the magnetic induction intensity. The application of steady magnetic field is beneficial to reduce the number of cracks on the surface and improve the microhardness of the coatings. The coating exhibits the best comprehensive property under the magnetic induction intensity of 0.2 T. Under the action of steady magnetic field, the electromagnetic braking effect and the thermoelectric magnetic fluid effect can both influence the laser cladding process. The surface morphology of the coating is mainly affected by the electromagnetic braking effect. The solidification microstructure is mainly controlled by the thermoelectric magnetic fluid effect.

Keywords

• Laser cladding
• Steady magnetic field
• Ni-based alloy coating
• Microstructure
• Microhardness
• Crack